At the start of their business day, from the depths of abandoned buildings and secluded alleyways, drug dealers will hand out “testers” — samples from a batch of drugs intended to gauge their potency and act as a marketing ploy.

People, some of whom have ended up in Baltimore from places as far-flung as Florida, line up for a chance to get high. Often homeless and cash-strapped, they see a tester as a chance to stave off debilitating vomiting and diarrhea from drug withdrawal. While every high carries a deadly risk, testers can be especially dangerous in an increasingly unpredictable drug supply.

This scene plays out day after day in open air drug markets in the Penn North neighborhood of West Baltimore, according to Donna Bruce, a community advocate who has worked there for years to connect people to treatment and other resources.

Though authorities are still investigating what caused a mass overdose event in the neighborhood, Bruce and many others in the community believe it was an especially dangerous batch of testers that hospitalized more than two dozen people on Thursday. Community workers who serve people who use drugs immediately began alerting their networks to avoid using testers from the area, they said.

What is clear is that a quick and forceful response from both the city and community organizations from every corner of Baltimore has so far prevented any fatalities.

Audio from emergency dispatches show a single call for help for a 27-year-old woman quickly spiraled into a much larger crisis.

“They keep pointing out people, and the medics keep taking them,” one officer said to dispatchers, noting a need for more emergency vehicles.

First responders found people lying unconscious at a bus stop, behind a pharmacy and even in the parking lot of a funeral home.

Emergency workers and volunteers scoured nearby blocks, searching 177 vacant buildings by the day’s end, said Mayor Brandon Scott on Friday. At least 27 people, ages 25 to 55, were transported to eight area hospitals, according to Baltimore Fire Department officials.

Overdoses at this scale were shocking even to veteran outreach workers like Bruce, who has struggled with addiction herself and lost a son to a drug overdose in the very same streets.

“I have never seen anything like this in my life,” she said while handing out boxes of overdose reversal drug Narcan in front of the Penn North library on Friday morning, adding, “I am just speechless right now.”

In recent years, Baltimore’s fatal overdose rate has far exceeded that of any other large cities’ in the U.S., stories by The Banner and The New York Times highlighted last year. People have died from overdoses on a third of city blocks at an average rate of two to three a day. While the crisis mounted, top city leaders were focused more on other pressing issues and there was little additional effort on addressing overdoses, reporting showed.

But since the city began winning hundreds of millions of dollars through a lawsuit against opioid manufacturers and distributors last year, overdoses have become a larger public priority.

City officials said Thursday’s response to the mass overdoses was “all hands on deck.” While the scene around Penn North may have appeared chaotic, J.D. Merrill, deputy chief of staff to Scott, said city agencies coordinated with the state, Baltimore County and 16 community organizations to canvas the area and administer naloxone.

“Medics saved people, police officers saved people, people saved people,” Merrill, who was on scene from morning until about 10:30 p.m., said in an interview.

“It was really remarkable” that no one died, Merrill added. The ability to coordinate so many resources so quickly is a testament to the planning and organization that has been going on behind the scenes for months, Merrill said.

“It’s not as public, it’s not as visible, but the process that we went through [Thursday] is a process that we go through very frequently,” Merrill said. “The size and scale of this is not something we’re as accustomed to. But the response effort yesterday showed that we have the right team and the right systems to be able to respond at scale when necessary.”

In recent weeks, officials committed $36.7 million to various community organizations and city agencies fighting the crisis, released a draft of a strategic plan to reduce overdoses by 40% in 15 years and began holding public hearings to discuss the toll of addiction.

Candy Kerr, a spokesperson for the Baltimore Harm Reduction Coalition, a group that serves people who use drugs, applauded the city’s coordination in the wake of Thursday’s emergency, but wished the urgent response could have come sooner.

“It’s unfortunate that it took a mass overdose event to have this kind of response to an area that has been exposed to overdoses for the last 30 years,” Kerr said. “For people who work on the ground and who live in the community, it feels like too little too late.”

Kerr’s group does work called harm reduction. Their focus is not on abstinence, but rather finding ways to keep people safe in the depths of addiction. They hand out clean needles, help people find housing and get them into treatment when they are ready.

They believe harm reduction is the key to preventing more overdose deaths in Baltimore, starting with widely distributing and training people to use naloxone, also known by its brand name Narcan, a nasal spray that can reverse overdoses in mere minutes.

The overdoses came a day after the City Council held a long-awaited hearing on the issue, throwing the breadth and scope of the overdose crisis into stark relief. Councilwoman Phylicia Porter, chair of the Public Health and Environment Committee, called Thursday a painful reminder of the need for expanded harm reduction efforts and for continued investment in community-based solutions.

“Yesterday’s tragedy brings a renewed sense of urgency to this crisis, but it also echoes what our communities have been saying for generations,” Porter wrote in an email. She said the stigma surrounding overdoses and lack of political will to address them needs to be resolved.

Porter said she, along with the Scott administration and the council will continue to address the crisis “incrementally, sustainably, and with the people of Baltimore at the center.”

One possible tool is the creation of supervised drug consumption sites, also called overdose prevention centers. For years, a community coalition and the Scott administration has unsuccessfully sought legislative approval to operate centers where people who use drugs can do so under supervision of community organizations. Other places, like New York, have similar programs and those centers have led to a direct decrease in the number of fatal overdoses, Scott has said previously.

People who go to those sites would have access to naloxone, fentanyl test strips and the opportunity to seek food, shelter and, if they want it, the ability to explore possible treatment for substance use.

City Councilman Ryan Dorsey, who has his own personal history of substance use and is sometimes reticent to speak on the topic, said at Wednesday’s council hearing that establishing overdose prevention centers is critical to the city’s path forward.

“I want for us to not use soft pedaling language when we talk about this, that we as a city actually need to be just very clear: We need overdose prevention sites. We need overdose prevention centers. We’ve been talking about it for long enough,” Dorsey said.

Every time a bill to establish these sites is introduced it has largely been dead on arrival, with none making it out of committee — even those backed by Scott and with support from delegates across Maryland.

But the city’s collective response Thursday essentially mirrored the kind of services and assistance available at such centers, only in an emergent setting.

Molly Greenberg, a community health nurse for Health Care for the Homeless, had rushed to Penn North Thursday after receiving a call for more community assistance.

Upon arrival, Greenberg said she saw nurses monitoring the vitals of people who had used drugs, workers offering naloxone and drug testing strips to everyone who walked past and programs offering to bring people to treatment.

“I hope this is a wake-up call for every part of the city,” Greenberg said. “There is so much more we could be doing, and we have the resources to do it now.”